煤焦在燃烧过程中孔隙结构变化的模拟

煤焦在燃烧过程中的物理特性，如比表面积和孔径分布会发生连续变化，直接测量煤焦在燃烧过程中的孔隙结构变化很困难，但可以通过合适的数学模型来观察，二维的圆柱孔模型已大量用来对煤焦气化与燃烧过程中表面积和孔隙结构的变化进行模拟，这个模型把孔隙分成两大部分－－大孔与小孔，因为小孔构成比表面的绝大部分，所以在反应过程中比表面积的变化可以由单一小孔模型来拟合，本文采用了用Ｔｓｅｎｇ和Ｅｄｇａｒ提出的孔模型对几     

Monte—Carlo model of the diffusion-limited reaction kinetics in microheterogeneous media. Comparison with the experimental plots of the forward and backward electron phototransfer kinetics on the pore diameter in silica gel

The kinetics of the diffusion-limited decay reaction A + B B was simulated by the Monte—Carlo method on a two-dimensional square lattice with defects presented by randomly distributed sites. The cases were considered where [B] [A] at the random initial distribution (quenching reaction) and [B] = [A] with the initial distribution of the A and B particles on neighboring sites (geminate recombination). The kinetic curves were approximated by the simplest analytical equation [A]/[A]₀ = (1 – )exp[–(kt)^1–h ] + (where k and are constants). The plots of the heterogeneity parameter (h) and time-averaged first-order rate constant vs. concentration of defects (p) or B particles (in the case of quenching) were obtained and compared with similar correlations obtained earlier by the experimental study of the kinetics of forward (quenching reaction) and backward (geminate recombination) electron phototransfer on the surface of different porous silica gels. The experimental plots of h vs. silica gel porosity are in satisfactory agreement with the plots of h vs. p in the model space, if the fraction of volume inaccessible for reactants, calculated from the free silica gel volume, is chosen as the p parameter for silica gel.Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1536–1541, August, 2004.     

Pore formation during the pyrolysis of C-Nb2O5 and C-Ta2O5 xerogels

Binary organic-inorganic gels have been prepared by mixing a carbonaceous hydrosol and a Nb₂O₅ or Ta₂O₅ sol derived by hydrolysis of the alkoxides. The gels are pyrolyzed under an inert atmosphere into precursors in which carbon and the metal oxides are mixed very intimately. High temperature treatment converts the precursors into the cubic face centered carbides. The precursors as well as the carbides have been shown to be micro- and mesoporous materials. Measurements of nitrogen adsorption reveal a characteristic change of the shapes of the isotherms (Type I Type IV) and of the hysteresis loops (H4H2H1) during the thermal processes. Pore widening has been observed with rising temperature. The phenomena of crystallization, carbothermal reduction and sintering were found to control the pore shape and size. The results of the adsorption measurement correlate well with those of the thermoanalytical and X-ray diffraction studies.Dedicated to Professor Dr. rer.nat. Dr. h.c. Hubertus Nickel on the occasion of his 65th birthday     

Ethane adsorption in slit-shaped micropores: influence of molecule orientation on adsorption capacity

Adsorption of ethane in a slit shaped micropore system has been studied by Monte Carlo molecular simulation by considering this hydrocarbon as a two interacting sites molecule. Ethane adsorption in pore sizes from 0.41 to 1.66 nm was simulated at 303 K. Microscopic characteristics of the adsorbed phase have been studied for pores of different size, comparing two density profiles: the molecule centre of mass profile and the molecular interaction site profile. Averaged angle distribution of molecule positions with respect to the slit plane across the pore width has been also obtained by simulation. These results were related to ethane molecule packing efficiency, which is also related to the adsorption capacity in terms of the adsorbed phase density. Packing efficiency presents an oscillation shape as the result of the adsorbate disorder inside the pore. Pressure influence on the adsorption has been studied by following pore filling by simulation. When pore condensation takes place and for pressures above condensation, fluid-fluid interactions are determinant in molecule disorder observed between the two adsorbed layers.     

Selective water sorbents for multiple applications, 3. CaCl2 solution confined in micro- and mesoporous silica gels: Pore size effect on the “solidification-melting” diagram

In this communication we present a low-temperature “solidification-melting” phase diagram for CaCl₂/H₂O solutions confined in KSK and KSM silica gels. At salt concentrations of 0–48 wt. %, the diagram has been found to lie below the diagram reported for the bulk system by 15–30°C. It shows a depression of the solution melting point due to its confinment to the pores. Several other peculiarities of melting and solidification in this system are also reported and discussed. Beside fundamental interest, the data obtained could be of importance in many commercial areas such as refrigeration, accumulation of low temperature heat, frost prevention in building materials,etc.     

计入孔隙结构影响的复层含油轴承润滑特性分析

基于Darcy定律和Kozeny-Carman孔隙方程,建立多孔质复层含油轴承的流体润滑模型,利用有限差分法数值模拟,分析复层结构和孔隙参数对含油轴承润滑性能的影响.得出结论如下:复层含油轴承润滑性能随轴承高度增大而变差,随孔隙率减小而变好,当总孔隙率一定时,较低的表层孔隙率有利于提高复层含油轴承润滑性能.因此设计复层含油轴承时,在保证一定孔隙含油量的前提下,应尽可能减小表层孔隙率.研究工作为复层含油轴承摩擦学性能分析与结构设计提供一定的理论基础.     

Formylated polystyrene for the fabrication of pore selective aldehyde group functionalized honeycomb patterned porous polystyrene films

Formylated polystyrene (PS‐CHO) was synthesized by chemical modification of polystyrene (PS) for the fabrication of honeycomb patterned (HCP) porous PS films with aldehyde group functionalized pores via breath figure method under humid conditions. The incorporation of hydrophilic aldehyde group affected the hydrophobicity of PS solution and assisted the self‐assembly of PS‐CHO toward pore. The presence of aldehyde groups in the films were proved by the post treatment with Tollens's reagent, which results in silver decoration at pores. The morphology of the films before and after silver decoration was studied by scanning electron microscopy analysis. The pore selectively self‐assembled aldehyde groups in the patterned porous films can have many applications as a reactive substrate in biomaterials and chemical moieties adhesion. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2018 , 56, 1181–1192     

The catalytic performance study of polymerized ionic liquid synthesized in different conditions on alkylation of o‐Xylene with styrene

In this work, a series of novel acidic polymerized ionic liquids were used as heterogeneous catalyst for alkylation of o‐Xylene with styrene. And the effect of the amount of initiator and the type of acid used for ion exchange on catalyst structure and the catalytic performance of catalysts for alkylation were studied thoroughly. The experiment results show: when the percentage of the amount of initiator in the total material is 3%, the polymerized ionic liquid catalyst MPM‐SO₃H‐[C₃V][SO₃CF₃] has the most uniform with a specific surface area of 97.30 m²/g and a pore volume of 0.35 cm³/g. Benefiting from the unique structure features, MPM‐SO₃H‐[C₃V][SO₃CF₃] manifested an excellent catalytic performance for alkylation of o‐Xylene with styrene, along with the conversion of styrene was 96.8% and the yield of 1‐Phenyl‐1‐ortho‐xylene ethane was 94.7%. Therefore, this work provides a novel reference to the synthesis of polymerized ionic liquids and clearly explains the advantage of novel acidic polymerized ionic liquids on alkylation.     

Effect of the structure of titanium–magnesium catalysts on the morphology of polyethylene produced

The structure and formation of polyethylene (PE) particles on supported titanium–magnesium catalysts having different structural characteristics (sizes of microcrystallites, mesopores, and subparticles) were studied for the first time. Scanning electron microscopy was used to identify structural elements of the polymer particles formed over such catalysts and to reveal morphological changes in the growing polymer particles when the yield was increased from approximately 0.2 g PE/g catalyst to approximately 13 kg PE/g catalyst. A relationship was found between structural characteristics of the porous catalyst particles, morphology of the nascent polymer particles, and bulk density of the polymer powder. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 2298–2308     

Surface Modification of Bituminous Coal and Its Effects on Methane Adsorption

This paper studied the role of O‐containing groups over the coal surface in methane adsorption. The coal was modified with H₂SO₄, (NH₄)₂S₂O₈ or H₂SO₄/(NH₄)₂S₂O₈), respectively, to introduce O‐containing functional groups, and characterized by proximate analysis, ultimate analysis, Boehm titration, X‐ray photoelectron spectroscopy (XPS) and nitrogen adsorption. The results of ultimate analysis, Boehm titration and XPS indicate that there were increases in terms of both the content of oxygen and the quantities of O‐containing groups over the modified coals surface, especially for the carboxyl. Nitrogen adsorption shows that the modified coals possessed higher surface area and pore volume than that of 0‐XQ. The methane adsorption data were measured at 298 K at pressures up to 4.0 MPa by the volumetric method and fitted well by Langmuir model. Experimental results implied that O‐containing groups and pore structure affected methane adsorption. The adsorption capacities decreased as increasing quantities of O‐containing groups.